Cleaning up elkscmd and adding help text - Questions

[Nils Stec <nils.stec@gmail.com>]

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Hi,

i started to write some patches, at the moment 2. Now it's the time to 
ask you guys some questions about that.

I wrote a patch for cat which shows the user some usage-information.
Jody Bruchon used write() for this purpose, other tools are using 
fprintf(stderr, ....).
I don't know which i should prefer. In my opinion i would rather use 
fprintf.
STDERR should be the output for operations, right?

I wrote a second patch, which adds some more functionality to cp.
It adds three command-line-options:
     -v    be verbose
     -i     be interactive, ask before overwriting
     -n    don't overwrite files

i want to add 3 more options:
     -u    update-only (only overwrite if source is newer)
     -b    make a backup if destination file already exists
     -f     force, if destfile cannot be opened, remove it, try again.


Is this the right way to write code for this project? It's the first 
time I'm doing this in here and i don't wan't to do things wrong...

I think these two patches are still just drafts - i send them because i 
want to show, i know theres more work to do on this two patches.

Nils

[-- Attachment #2: patch-usage-cat.diff --]
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diff --git a/elkscmd/file_utils/cat.c b/elkscmd/file_utils/cat.c
index e8b9576..d4616c7 100644
--- a/elkscmd/file_utils/cat.c
+++ b/elkscmd/file_utils/cat.c
@@ -35,6 +35,8 @@ int main(int argc, char **argv)
 		if (dumpfile(STDIN_FILENO)) goto error_read;
 	} else {
 		for (i = 1; i < argc; i++) {
+			if(!strcmp(argv[1], "-h")) goto usage;
+
 			errno = 0;
 			fd = open(argv[i], O_RDONLY);
 			if (fd == -1) {
@@ -52,4 +54,11 @@ error_read:
 		argv[0], argv[i], strerror(errno));
 	close(fd);
 	exit(1);
+
+usage:
+	write(STDERR_FILENO, "concatentate file(s) or standard input to standard output.\n", 60);
+	write(STDERR_FILENO, "usage: cat [OPTIONS] [FILE]\n", 29);
+	write(STDERR_FILENO, "options: -h  help\n", 18);
+	write(STDERR_FILENO, "when no file is given or file is '-' STDIN is used for input.\n", 62);
+	exit(0);
 }

[-- Attachment #3: patch-cp-add_options_001.diff --]
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diff --git a/elkscmd/file_utils/cp.c b/elkscmd/file_utils/cp.c
index 6e23864..ed1e66c 100644
--- a/elkscmd/file_utils/cp.c
+++ b/elkscmd/file_utils/cp.c
@@ -22,9 +22,16 @@
 #include <errno.h>
 
 #define BUF_SIZE 4096
+#define NOT_OVERWRITING		0xABCD
 
 static char *buf;
 
+static unsigned int copy_count;
+
+/* we need some flags for command-line-options */
+static int option_no_overwrite;
+static int option_verbose;
+static int option_interactive;
 
 /*
  * Build a path name from the specified directory name and file name.
@@ -79,14 +86,26 @@ int copyfile(char *srcname, char *destname, int setmodes)
 	struct	stat	statbuf2;
 	struct	utimbuf	times;
 
-	if (stat(srcname, &statbuf1) < 0) {
+	if (stat(srcname, &statbuf1) < 0) {	// src nonexistent
 		perror(srcname);
 		return 0;
 	}
 
-	if (stat(destname, &statbuf2) < 0) {
+	if (stat(destname, &statbuf2) < 0) {	// dst nonexistent
 		statbuf2.st_ino = -1;
 		statbuf2.st_dev = -1;
+	} else {	// dst existent
+		if(option_no_overwrite) {
+			fprintf(stderr, "dest '%s' is existent, not overwriting\n", destname);
+			return NOT_OVERWRITING;
+		}
+		if(option_interactive) {
+			/* TODO fix this, getchar wants return and seems not to work properly */
+			//printf("really overwrite '%s'? (y/n) \n", destname);
+			//if(getchar() != 'y') {
+			//	return NOT_OVERWRITING;
+			//}
+		}
 	}
 
 	if ((statbuf1.st_dev == statbuf2.st_dev) &&
@@ -143,6 +162,12 @@ int copyfile(char *srcname, char *destname, int setmodes)
 		(void) utime(destname, &times);
 	}
 
+	if(option_verbose) {
+		printf("copied '%s' -> '%s'\n", srcname, destname);
+	}
+
+	copy_count++;
+
 	return 1;
 
 
@@ -157,37 +182,78 @@ error_exit:
 int main(int argc, char **argv)
 {
 	int	dirflag;
+	int     arg_counter;
+	int	options_counter;
+	int	retval;
+	unsigned int file_count;
 	char	*srcname;
 	char	*destname;
 	char	*lastarg;
 
 	if (argc < 3) goto usage;
 
-	lastarg = argv[argc - 1];
+	lastarg = argv[argc - 1];	// lastarg is copy destination
 
-	dirflag = isadir(lastarg);
+	dirflag = isadir(lastarg);	// is destination a directory?
+
+	// set defaults for options //
+	option_no_overwrite = 0;
+	option_verbose = 0;
+	option_interactive = 0;
+
+	// walk throug all args, see if there are options for copy-operation
+	// count options for later addition to arg-counter
+	arg_counter = 1;	// start at argv[1]
+	options_counter = 0;
+	while(arg_counter < argc) {
+		if(!strcmp(argv[arg_counter], "-n")) {
+			options_counter++;
+			option_no_overwrite = 1;
+		}
+		if(!strcmp(argv[arg_counter], "-v")) {
+			options_counter++;
+			option_verbose = 1;
+		}
+		if(!strcmp(argv[arg_counter], "-i")) {
+			options_counter++;
+			option_interactive = 1;
+		}
+		if(!strcmp(argv[arg_counter], "-h")) goto usage;
+		arg_counter++;
+	}
 
-	if ((argc > 3) && !dirflag) {
-		fprintf(stderr, "%s: not a directory\n", lastarg);
+	if((argc > (3+options_counter)) && !dirflag) { 	// can't copy more than one src-files into one dst-file
+		fprintf(stderr, "%s is not a directory\n", lastarg);
 		exit(1);
 	}
 
 	buf = malloc(BUF_SIZE);
-	while (argc-- > 2) {
-		srcname = argv[1];
+	copy_count = 0;
+	file_count = 0;
+	while (argc-- > (2+options_counter)) {
+		srcname = argv[options_counter+1+file_count];
 		destname = lastarg;
-		if (dirflag) destname = buildname(destname, srcname);
+		if(dirflag) destname = buildname(destname, srcname);
 
-		if (!copyfile(*++argv, destname, 0)) goto error_copy;
+		retval = copyfile(srcname, destname, 0);
+		if((!retval) && (!(retval == NOT_OVERWRITING))) goto error_copy;
+		file_count++;
 	}
 	free(buf);
+	if(option_verbose) printf("copy-count = %d\n", copy_count);
 	exit(0);
 
 error_copy:
 	fprintf(stderr, "Failed to copy %s -> %s\n", srcname, destname);
 	exit(1);
 usage:
-	fprintf(stderr, "usage: %s source_file dest_file\n", argv[0]);
-	fprintf(stderr, "       %s file1 file2 ... dest_directory\n", argv[0]);
+	fprintf(stderr, "usage: %s [options] source_file dest_file\n", argv[0]);
+	fprintf(stderr, "       %s [options] file1 file2 ... dest_directory\n", argv[0]);
+	fprintf(stderr, "options:  -b   make a backup of each exisiting destination file\n");
+	fprintf(stderr, "          -f   if a existing destination file cannot be opened, remove it and try again\n");
+	fprintf(stderr, "          -n   no overwriting\n");
+	fprintf(stderr, "          -v   be verbose\n");
+	fprintf(stderr, "          -i   interactive, prompt before overwrite\n");
+	fprintf(stderr, "          -u   copy only if source file is newer than destination file\n");
 	exit(1);
 }